On 24/04/16 13:47, Dong Aisheng wrote:
> On Fri, Apr 22, 2016 at 8:48 PM, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>> On 15/04/16 20:29, Dong Aisheng wrote:
>>> During card detection process, mmc core may sends commands
>>> to detect if card is still exist in mmc_rescan for removable
>>> card which may trigger mmc retuning process after a bit time
>>> of runtime pm suspend.
>>> Obviously this retuning process is meaningless for card remove
>>> case, so we disable mmc_retune in mmc_detect_change() for it.
>>> For card insert case, the mmc_retune will be enabled normally
>>> in its card initialization process later in mmc_execute_tuning().
>>> So disable it at first has no side effection.
>>
>> We don't assume that the card has been removed, which is why we send
>> commands to find out if it is still there. If it is still there, this
>> change will have incorrectly disabled re-tuning.
>>
>
> Do you mean the 'fake' card remove interrupt like caused by glitch?
Sure
> Yes, if that the card is still exist and re-tuning is wrongly disabled.
>
> So we could re-enable re-tuning for this special case?
> Something like:
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 41b1e76..e1990a8 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2607,6 +2607,8 @@ void mmc_rescan(struct work_struct *work)
>
> /* if there still is a card present, stop here */
> if (host->bus_ops != NULL) {
> + if (tuning_is_enabled_before())
> + mmc_retune_enable(host);
> mmc_bus_put(host);
> goto out;
> }
>
>
>> Do you have an actual problem with the way it works now?
>>
>
> No actual problems now.
So let's not spend time on it.
> I just observe a lot tuning commands keep sending although the card is already
> removed which seems a bit meaningless.
> And most tuning execution process is executed with sin_lock_irqsave, i'm not
> sure if the mass tuning commands may affect the system when CPU is busy.
> What do you think?
sdhci spin lock is unlocked while waiting for tuning commands.
>
> Regards
> Dong Aisheng
>
>>>
>>> CC: stable <stable@xxxxxxxxxxxxxxx>
>>> Signed-off-by: Dong Aisheng <aisheng.dong@xxxxxxx>
>>> ---
>>> drivers/mmc/core/core.c | 1 +
>>> 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>>> index 52bfaf0..76d0802 100644
>>> --- a/drivers/mmc/core/core.c
>>> +++ b/drivers/mmc/core/core.c
>>> @@ -1888,6 +1888,7 @@ static void _mmc_detect_change(struct mmc_host *host, unsigned long delay,
>>> pm_wakeup_event(mmc_dev(host), 5000);
>>>
>>> host->detect_change = 1;
>>> + mmc_retune_disable(host);
>>> mmc_schedule_delayed_work(&host->detect, delay);
>>> }
>>>
>>>
>>
>
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